1. Field of the Invention
This invention relates in general to a subterranean connector for use in a wellbore. More particularly, the present invention is directed to a connector used to provide power to a submersible motor. Yet more particularly, the present invention provides a electrical submersible pump connector configured to be pressure compensated.
2. Description of the Related Art
A common type of electrical submersible pump comprises a centrifugal pump suspended on a string of tubing within a casing of the well. The pump is driven by a downhole electrical motor, normally a three-phase AC type. A power line extends from a power source at the surface alongside the tubing to the motor to supply power.
Typically the power line is made up of two sections, an external motor lead (external to the motor) and a power cable. The external motor lead has a plug on its lower end known as a “pothead” that secures to a receptacle known as a “pothole” at the upper end of the electrical motor. The external motor lead typically has three conductors that are insulated and located within a single elastomeric jacket that is extruded around the assembled insulated conductors. Metallic outer armor may wrap around the jacket of the external motor lead to avoid damage to the motor lead while running the pump assembly into the well. The external motor lead extends upward beyond the pump, for example, from 10 to 80 ft. The total of the external motor lead and pothead is known as the motor lead extension (MLE). The lead could exceed 80 ft or be shorter than 10 ft depending on the application. A splice connects the external motor lead to the power cable. The external motor lead is flat and smaller in dimension than the power cable so that it can pass between the pump assembly and the casing.
The power cable typically comprises three conductors, each having one or more layers of insulation. An elastomeric jacket is usually extruded over the assembled conductors. In some cases, the insulated conductors are encased in lead. The insulated conductors are arranged either in a flat side-by-side configuration, or in a round configuration spaced 120 degrees apart from each other relative to a longitudinal axis of the power cable. A metallic armor is typically wrapped around the jacket to form the exterior of the power cable.
In some wells, the formation pressures are quite high and can vary, causing a significant differential in pressure between the internal pressure of the motor and the internal pressure of the pothead and/or pothead connector. Therefore, it would be beneficial to have a motor electrical connection design that is operable to compensate for internal differential pressure between the connector in the motor.